Extraction of cellulose nanocrystals from date seeds using transition metal complex-assisted hydrochloric acid hydrolysis

In this study, the role of a transition metal complex in improving hydrolysis efficiency during nanocellulose production was analysed. Cellulose nanocrystals (CNCs) were extracted from date seeds by incorporating a copper metal complex during HCl hydrolysis. In contrast to traditional HCl hydrolysis at moderate conditions, which yielded only microcrystalline cellulose (MCC), this approach resulted in the extraction of CNCs with a 10 % improved yield compared to MCC. Morphological analysis using scanning electron microscopy revealed semi-spherical shaped particles, while transmission electron microscopy showed CNCs with a particle size ranging from 70 to 80 nm. Dynamic light scattering analysis indicated a significant reduction in average particle size from 900 nm to 121 nm, highlighting the remarkable efficiency of using the copper metal complex in combination with HCl to improve yield and particle size. Energy dispersive X-ray spectroscopy analysis confirmed the purity of the CNCs, with no residual copper detected. Thermal analysis demonstrated the high stability of the CNCs, with an initial decomposition temperature (T_onset) of 274.02 °C and an activation energy (E_a) of 219.90 kJ/mol. X-ray diffraction analysis revealed that the CNCs exhibited high degree of crystallinity (C_rl=72.03 %). Disseminating these research findings will significantly impact the CNCs production industry, facilitating improved yields and the production of nano-sized fibers through the utilization of transition metal complexes alongside hydrolysis solvents.